URUMQI, China: Saying terrorists will be “hunted down and punished,” authorities launched a security crackdown on Saturday in China’s Muslim northwest, site of a deadly bombing that has the central government in far-off Beijing bracing against violence that some say heralds a rise of organized extremism in the region.

Thursday’s bombing at a morning street market selling vegetables and other produce in Urumqi, capital of the Xinjiang region, killed at least 43 people and left the region’s ethnic Chinese on edge.

“We don’t know why there have been explosions, but we are definitely worried about personal safety,” said Luo Guiyou, a member of China’s Han ethnic majority who manages an auto parts store.

Police announced names of five people blamed for the attack and said they were part of a “terrorist gang.” Based on their names, all appeared to be Uighurs, the region’s most populous Muslim minority. Police said that four of the assailants were killed in the bombing and that the fifth was captured Thursday night.

An anti-terrorism campaign with Xinjiang “as the major battlefield” will target religious extremist groups, underground gun workshops and “terrorist training camps,” the official Xinhua News Agency said. “Terrorists and extremists will be hunted down and punished.”

Beijing blames unrest on extremists with foreign ties, but Uighur activists say tensions are fueled by an influx of migrants from China’s dominant Han ethnic group and discriminatory government policies. Thursday’s bombing has raised questions about whether Beijing’s tightening grip might be feeding anti-China anger and a rise of organized terrorism in the country.

“The violence is an indication that people are willing to take more drastic measures to express their opposition,” said David Brophy, a Xinjiang historian at the University of Sydney. A heavy-handed response might backfire by inciting sympathy from Central Asian radicals about “the plight of Muslims in Xinjiang,” said Ahmed A.S. Hashim, a terrorism expert at Singapore’s Nanyang Technical University.

“In fact, groups like al-Qaeda and others are now beginning to think that China could be a new oppressor of the Muslim world,” he said. In Beijing, police announced that they were canceling vacations for officers and would step up patrols at train stations, schools, hospitals and markets. A measure under which passengers at stations in central Beijing are required to undergo security checks will be extended to three additional stations, the city government said. Passengers at all stations already are required to submit handbags and parcels for X-ray examination under rules imposed ahead of the 2008 Summer Olympics in Beijing.

Thursday’s violence was the deadliest single attack in Xinjiang’s recent history, and the latest of several that have targeted civilians in contrast to a past pattern of targeting police and officials. It was the highest death toll since several days of rioting in Urumqi in 2009 between Uighurs and members of China’s dominant Han ethnic group left nearly 200 people dead.

On Saturday, paramilitary police with rifles stood every 20 meters along the streets around where the bombing took place. The street where the market was located was closed to vehicle traffic. Li Shengli, who was in Urumqi on a business trip from Shanghai, brought three stems of yellow chrysanthemums.

“I am here to remember the dead,” he said. He was quickly pulled away by an official who warned him not to talk to reporters. The family of one victim, Lu Xiangwang, a 58-year-old driving teacher, said they were waiting to receive his body.

In his parents’ apartment near the market, Lu’s mother sat sobbing on a couch, surrounded by relatives. A neighbor, Ji Jinzhu, said Lu spent the night before the attack at the apartment to look after his ill father.

“He was hit by an explosive just moments after he stepped outside this residential compound into the street,” Ji said. “The father is feeling very guilty because had it not been for his illness, his son would not have had to come to take care of him.”

Ji, 80, said he was shopping in the crowded market on Thursday morning with his wife when the two off-road vehicles raced into the street.

“When they passed me, I heard explosions and saw flames going up into the sky and smoke filling up the air,” he said. An Associated Press reporter who visited a Uighur neighborhood was escorted away by 11 uniformed police officers and street wardens. The influx of ethnic Han Chinese has left Uighurs (pronounced WEE-’gurs) feeling marginalized in their homeland and excluded from decision-making.